The field of this invention is personal hygiene. More particularly, the field of this invention is toothbrushes, and especially those with disposable or replaceable parts.
The humble tooth brush has long been a target of inventive art. In particular, it has long been recognized that the bristle or brush section generally wears down faster than the handle, rendering the brush unusable, and generally requiring the brush""s complete disposal and replacement. Numerous methods have thereby been proposed which allow the toothbrush head or bristle portion to be replaced while reusing the handle.
Today, however, an examination of the products available in any drugstore will reveal that with the exception of expensive motorized toothbrushes, the disposable head concept has not been a commercial success. The reason for this lack of success is not hard to divine: the minor expense of a new molded plastic or rubber handle with integral bristles removes the economic incentive to provide a more expensive reusable handle. Despite the apparent waste of material, economics still favors disposal of the simple, single-piece toothbrush.
Also, a toothbrush handle having been in service long enough to wear down the bristles, though itself not actually substantially worn, may appear to be in used condition through hard water or dried toothpaste deposits. These deposits form even with regular rinsing, and so create an additional incentive to throw away the entire inexpensive brush assembly away rather than clean the handle. The user enjoys the xe2x80x9cinconspicuous consumptionxe2x80x9d of a new toothbrush.
There may be a reason other than economics to provide a method of replacing of the brush head, and at more frequent intervals than required by the wear of the bristles: hygiene. Studies have shown that a toothbrush in daily use harbors both minute food particles and bacteria. For this reason a user may want to replace the bristles more frequently than dictated by wear. A consumer may also occasionally want to allow a person whom he does not wish to risk cross-contamination with to borrow his toothbrush.
Consumers who wish to replace the bristles at high frequency may find the expense of using a fresh single piece toothbrush each time to be unacceptable. Therefore, while simple economics may not support the concept of reusing a handle when the bristles have been worn and require replacement, there may be demand for such a product for more frequent bristle exchanges, analogous to the provision of a fresh dinner napkin with each diner and each meal. There is no product on the market which permits convenient and economical replacement of the bristles of a toothbrush at frequent intervals.
For purposes of hygienic bristle exchange, all disposable head toothbrushes known to the inventor have one or more disadvantages. Existing art either requires the user to handle the bristle mounting structure directly, thus providing a ready source of cross-contamination and tending to defeat the purpose of hygienic interchange, or require considerable dexterity in manipulating springs and clips and other small parts to change heads, or lack a secure way of securing the disposable head to the handle, risking unintended disengagement while brushing, or share some combination of these drawbacks which would be advantageous to overcome. One early model for example slides a brush head onto a grooved sheet metal track, only secured by friction, which track might severely injure the gums of a user should the brush head come off during vigorous brushing.
It therefore would be advantageous to provide a toothbrush with replaceable bristles and supporting structure, which was simple and economical enough for frequent replacement, which minimized handling requirements for the replaceable parts, which provided a secure lock or engagement of a replaceable part to prevent unintended disengagement and overcame the other limitations of the prior art.
It would also be advantageous to provide a product having these features which was easy and enjoyable for a user to operate, and thereby encouraged frequent bristle replacement, both maximizing the hygienic advantages to be obtained from using the product, and increasing the economic advantages to the manufacturer of the device.
A dental care instrument or toothbrush has at least two elements in a handle or grip that rotate relative to one another. The rotating elements are provided with knurled or other frictional gripping surfaces to facilitate gripping by a user and to enable the user to impart opposing rotational motion to the segments. The relatively rotating elements may be portion of the handle which the user grasps in the process of brushing the teeth and a knob mounted on an end of the handle away from the brush head, for the purpose of operating the mechanism to replace the brush head.
The handle is hollow, and contains an internal mechanical linkage. Application of opposing rotational motion to the rotating elements causes, via the internal mechanical linkage, a rotation of a U-shaped frame or track located on the opposite or head end of the instrument out of a longitudinal axis of the head, thereby allowing replacement of bristles mounted on a grooved bristle bed which slides onto and off the U-shaped track.
In this patent application, the term xe2x80x9cbrush headxe2x80x9d is used synonymously with the term xe2x80x9cbristle bedxe2x80x9d and should not be confused with the head of the toothbrush, which is a section of the toothbrush in an applicator section of the toothbrush. The applicator section of the toothbrush comprises a head and a neck whereby the head is connected to the toothbrush handle. The track is adapted to engage a disposable bristle bed, such as by the track engaging a portion of the bed having grooves. When the U-shaped track is rotated out of the longitudinal axis of the head a disposable bristle bed may be readily engaged or disengaged from the track by sliding. When the track is rotated back into the axis of the head, the track and bed lock in a closed position at the end of rotational travel when the track or bristle bed engage a lip or stop located on a tip of the head, in order to prevent the bristle bed from becoming disengaged.
The arrangement of the invention prevents unintended disengagement of the bristle bed by employing a locking surface to prevent travel of the bed in a closed position of the track and not relying entirely on friction to secure the bed, unlike U.S. Pat. No. 1,092,014 to Briggs which shows no evidence of contemplating other than a simple frictional fit. Rotation of the track in Briggs is solely a means of allowing the user to select a variable angle of brush head for the user""s brushing preference. The rotation of the track has nothing to do with removal of the bristles, which may be removed and replaced with the track at any angle. In the present invention rotation of the track is provided not to alter the geometry of the brush for brushing, but entirely in the service of removal and replacement of the bristles, which are locked in by the lip or stop when the track is in a first, closed, position and removable only when the track is in a second, open position.
In the unlikely event that the tracks moves off the closed position during use, the user will notice the bristle bed shifting and return the brush head to its use or service position. It is extremely unlikely that sufficient unintentional rotation of the track could occur to allow the bristle bed to become inadvertently disengaged from the track. This is partially due to internal gearing, to be described below, which prevents rotation of the track by pushing the track directly. Instead, one has to turn the knob. The combination of this gearing and a fiction fit of the bed or track with the lip is sufficient to prevent unintended movement of the brush head. However, snap fit or other locking devices may be added for additional security.
A bend or elbow is advantageously added to the toothbrush between the handle and the head, in a region called the neck, to allow a more natural brushing angle with respect to a user""s mouth, but this is geometry optional to the invention.
In a process of use, starting with an empty track fully rotated out the axis of the head to an open position, a user may open a sanitary package containing an individual brush head, for example, by ripping off an end closure of that package, and the replacement head may thereby be handled by the package or bag without the user contacting the bristles, while it is slid onto the track. The user then appropriately rotates the handle sections to cause the track to rotate back into the axis of the handle and engage in a use position, wherein the brush head is blocked from sliding movement by a stop on the end of the handle. The dental care instrument is now ready for brushing.
When a user later wishes to dispose of the used brush head, he reverses the operation by twisting the rotating section of the handle in the opposite direction, rotating the track out of the axis of the handle, and allowing removal of the brush head. It is not necessary for the user to grasp the brush head to remove it, however, since it may be simply flipped off into the garbage. Thereby it is possible for the user concerned about hygiene to both load and unload the unit without contaminating either himself or the bristles; a feature which also may be of use in institutional or medical settings.
Alternatively, replacement heads may be packaged with multiple units in a single closure, analogous to double edge razor blades, and in a manner adapted to allow removal of one unit by insertion of the prongs of the U-shaped track into the package to engage a single bristle head, which is then removed from the package using the toothbrush as a handle, and then locked into place as described above, as will be apparent to those skilled in the art.
The following important objects and advantages of the present invention are:
(1) To provide a toothbrush with a replaceable bristle bed;
(2) To provide a toothbrush with a replaceable bristle bed which operates in an economical way;
(3) To provide a toothbrush with a disposable bristle bed which minimizes the need to handle the old and new bristles on the part of a user effecting a replacement;
(4) To provide a method for replacing a toothbrush bristle bed which is simple for a user to operate;
(5) To provide a method for replacing a toothbrush bristle bed which a user can operate in an hygienic way, without contacting the new or used bristles;
(6) To provide a toothbrush with a disposable bed that carries bristles which bed slidably engages a track during use; and
(7) To provide a disposable bristle bed toothbrush and method of using the same which is enjoyable for a user, and encourages frequent bristle replacement.
These and other objects of the invention will become apparent from reading the attached specification.